LJWorld.com

An ominous story ran in Science magazine 25 years ago. It concerned a theory that dinosaurs became extinct 65 million years ago after an asteroid struck Earth and threw up a dust cloud that blocked the sun and changed the chemistry of the atmosphere.

Since then, scientists have paid increasing attention to extinction.

This spring, Kansas University received the largest federal grant in its history - a $19 million award from the National Science Foundation - to establish a center that will study the relationship between polar ice and global climate change.

Climate change, the depletion of natural resources and the spoiling of air and water - all of these worry people, even if they don't spend their idle hours fretting about extinction.

Still, there's plenty of evidence that scientists are busy thinking about it. Consider a few recent news items.

A KU astrophysicist and his colleagues have theorized that, about 433 million years ago, a brief, intense burst of gamma rays may have killed off more than half of all marine invertebrates, or creatures without spines.

A KU biologist documented that a rule of thumb used by biologists to predict species diversity holds true even for tiny water plants called phytoplankton. Having a good rule of thumb for predicting species diversity is crucial to monitoring species extinction.

A KU entomologist, witnessing the drop in monarch butterfly populations because of shrinking habitat and food sources, is trying to stimulate the creation of waystations along their migratory path.

Maybe alarm bells went off inside humans 25 years ago when we realized that a single asteroid may have relegated dinosaurs to the trashbin of history. That's a good thing.

Vigilance pays.

Nevertheless, there's an escape clause written into the natural order, a trump card held by evolution.

It can, given world enough and time, reinvent an organism - or at least something much like the original model. Students of fossil plants - KU's Tom Taylor is one of them - know that lichens already have been reinvented, at a minimum, five times during our planet's history. One species of saber-toothed tiger evolved and went extinct at least four times.

Of course sometimes we're just plain wrong thinking that something's extinct. Recently we found the long-lost ivory-billed woodpecker. Its nickname is the "Lord God bird" because of what overwhelmed birdwatchers sometimes exclaimed when they saw it. It's living up in a hardwood swamp in Arkansas ... for now.

In the end, the notion of "extinction" gives us plenty to ponder. Life hangs on by the fingernails, claws, talons. Life is burrowed so deeply into this planet, and niched so cleverly, that it's hard to imagine what might slaughter it all.

And even if that were to happen, death is not the end. A species, or something very like it, may rise again.

And again.

And again.